实际的地球介质十分复杂,远非当今人们所采用的理想模型可以概括,因为其属性和结构的变异是非均匀、非线性和各向异性的.在研究地球内部壳幔介质与结构、构造与属性差异、金属矿产资源和油、气、煤能源的勘查中,无论是区域构造格局、岩相和结构特征(如裂缝、破碎带、不同尺度的洞穴以及一些不规则几何体)均十分复杂.近年来基于成山、成盆、成矿、成岩和成灾研究的不断深化,对地下介质各向异性的研究受到广泛的关注.地震波动传播理论和介质与结构的物理属性研究结果表明:地震各向异性在成因上主要是由岩石、矿物和晶体的晶格优势取向、应力场异常变异和构造裂缝与深部物质运移造成的.为此,本文对14次地震各向异性会议的主体内涵进行分析,在此基础上,指出了在各向异性研究的发展进程中、特别是在应用中尚存在着的一些问题.在深化认识地球内部物质物理属性的基础上,探讨了s波分裂和偏振效应与地震各向异性与介质结构分区、构造活动,油气田勘探与岩相特征,裂隙与构造精细刻划和地震活动区(带)深部介质与构造环境的深层过程和动力学响应的关系.最后提出了地震各向异性在地球物理学发展中的作用和今后的任务.
The earth interior is so complex that it is impossible to describe it in a simple model, because its structure and property are inhomogeneous, nonlinear and anisotropic. The tectonic frame, lithology, and structural characteristics (such as fractures, broken belts, caves with various scales and irregular geometry) are all very complex in the exploring metal mineral, energy and the research of the structure and tectonics of the earth interior. Hence, much more attention has been paid to the anisotropy of the medium underground based on the deepen research in mountain formation, basin formation, mineral formation, rock formation and disaster formation. According to the research of physical properties of medium structure and seismic wave propagation theory, the seismic anisotropy is formed because of the existence of the preferred orientation of rocks, minerals, and crystal lattice, variation of the stress field, tectonic fractures and the substance movement in the deep earth. In this paper, the problems in the development, especially in the application of seismic anisotropy were raised based on the analysis of the main content of the 14 IWSAs in the world. On the basis of research on the properties oI the earth interior, we discussed relationships between the splitting of S waves, polarization effect, structure division and tectonic activities, exploration in oil and gas fields, deep process and dynamical response of the fine tectonics and earthquake activity areas (belts). At last, the effects and tasks of seismic anisotropy in the development of geophysics were raised.